Work vehicle with engine mounted rearwardly

ABSTRACT

A fuel system for a work vehicle including a fuel tank comprising a main tank body and an auxiliary tank body, a canister, and a fuel-gas introducing passage for connecting a top portion of the auxiliary tank body to the canister. The top portion of the auxiliary tank body is located higher than the main tank body when the fuel tank is installed on the work vehicle. A fuel filling pipe extends through the top portion of the auxiliary tank body and has a first end arranged outside the auxiliary tank body and a second end arranged within the auxiliary tank body.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a U.S. continuation of U.S. patentapplication Ser. No. 13/423,551 filed Mar. 19, 2012, the disclosure ofU.S. patent application Ser. No. 13/423,551 is hereby expresslyincorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a work vehicle including an engine anda fuel system mounted in a rear area of a vehicle frame extendingbetween a right and left rear wheels rearwardly of a driver's seat.

BACKGROUND ART

U.S. Patent Application Publication No. US 2010/0242924 discloses a lawnmower including a rear frame formed of a right and left pair of sidemembers made of sheet metal and a mounting surface supported rearwardlyof the right and left side members, for example. An air-cooled engine ismounted on the mounting surface with an output shaft thereof projectingforward of a vehicle body. A muffler is disposed in a transverseposition rearwardly of the engine. Fuel tanks are provided above theright and left rear wheels, respectively, to act as a fuel system.Evaporated gas separator tanks and canisters are disposed between thefuel tanks and the engine to allow fuel gas evaporated within the fueltanks to combust in the engine. Each of the evaporated gas separatortanks is configured to recover fuel gas having evaporated within thefuel tank and direct it to the canister, and is disposed in a gaspassageway between each fuel tank and each canister. The canisters areprovided under the right and left fuel tanks in association with theright and left fuel tanks, respectively, to be distributed in the rightand left sides of a rear portion of an oil cooler in a cooling airpassageway at positions that are spaced from each other substantiallyequidistantly from a lateral center line of a traveling vehicle body. Insuch a conventional fuel system, it is required to provide long hosesfor connecting between the fuel tanks, canisters and engine, whichresults in a complicated hose arrangement.

Further, U.S. Pat. No. 7,849,837 B2 discloses a lawn mower provided witha fuel system for performing evaporated fuel processing. Type of lawnmower includes a fuel tank disposed on a side of an engine mountedrearwardly of a vehicle frame, and a battery unit fixed to the vehicleframe rearwardly of the engine. On the fuel tank is mounted a canistercommunicating with an upper inner space of the fuel tank. The canisterhas a purge conduit extending from the opposite side of a portcommunicating with the fuel tank and fixed to a purge joint at a lowerend thereof. In this arrangement, the canister is provided above thefuel tank, which inevitably limits a space for accommodating thecanister. As a result, restrictions may be imposed in the size as wellas the maintenance and inspection of the canister.

SUMMARY OF INVENTION

The object of the present invention is to provide a work vehicle inwhich an engine and a fuel system are properly arranged for improvingeffective use of space and achieving simplification of the maintenanceand inspection.

In order to achieve the above-noted object, a work vehicle according tothe present invention comprises a vehicle frame extending between aright and left pair of rear wheels; a horizontal mounting surfacedefined in the vehicle frame in a peripheral area of the rear wheels; anengine arranged on the mounting surface at a central portion thereof ina transverse direction of the vehicle; a fuel tank including a main tankbody mounted under a driver's seat and an auxiliary tank body mounted onone lateral side of the engine in the transverse direction of thevehicle; and a canister mounted on the mounting surface adjacent to theengine on one lateral side of the engine and rearwardly of and adjacentto the auxiliary fuel tank.

With the above-noted arrangement, the fuel tank is divided into the maintank body and the auxiliary tank body that are provided spacious areas,respectively, such as under the driver's seat and the side of theengine, as a result of which good efficiency of spatial use can beachieved. Further, the fuel tank, vertical engine and canister areadjacently provided so that they do not substantially overlap each otheras viewed from the top. Since the particularly heavy engine is providedvertically in the central portion in the transverse direction of thevehicle, the stability of the work vehicle is secured. Further, theengine, fuel tank and canister are adjacently disposed, which candiminish a piping layout extending between those devices. In addition,the fuel tank is divided into the main tank body mounted under thedriver's seat and the auxiliary tank body mounted adjacent to the fueltank and the canister to effectively use the space, which provides alarge capacity for the fuel tank.

In a preferred embodiment, at least a large part of the main tank bodyis covered by the driver's seat, thereby to protect the main tankportion. Further, the auxiliary tank portion is allowed to extendupwardly from a side of the driver's seat, which improves theoil-feeding performance.

When a battery unit is provided rearwardly of the canister in view ofthe size of the canister smaller than the engine, the canister and thebattery unit are longitudinally arranged, which further miniaturizes theconstruction.

In addition, a muffler is mounted on the other lateral side of theengine, that is a side of the vehicle, which enhances thermal isolationand cooling properties of the muffler.

BRIEF DESCRIPTION OF DRAWINGS

In the drawings, there is illustrated the following.

FIG. 1 is a perspective view from an upper diagonal direction of a workvehicle according to the present invention showing a basic arrangementof an engine and a fuel system mounted in a rear area of the vehicle;

FIG. 2 is a top plan view of the basic arrangement of the engine and thefuel system mounted in the rear area of the vehicle;

FIG. 3 is a perspective of a lawn mower exemplifying the work vehicleaccording to the present invention;

FIG. 4 is a side view of the lawn mower in FIG. 3;

FIG. 5 is a top plan view of the lawn mower in FIG. 3;

FIG. 6 is a perspective view of the fuel tank;

FIG. 7 is a sectional view of an auxiliary tank body of the fuel tank;

FIG. 8 is a top plan view showing a mounting structure of the fuel tank;

FIG. 9 is a schematic view showing a power transmission system.

FIG. 10 is a perspective view of a lawn mower according to a modifiedembodiment of the present invention;

FIG. 11 is a perspective view showing a mounting structure of the fueltank according to a further modified embodiment of the presentinvention;

FIG. 12 is a perspective view of the fuel tank according to the furthermodified embodiment of the present invention; and

FIG. 13 is a perspective view of the auxiliary tank body of the fueltank according to the further modified embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

Prior to describing specific embodiments of a work vehicle according tothe present invention, a basic arrangement of an engine and a fuelsystem mounted in a rear area of the vehicle will be described first inreference to schematic views shown in FIGS. 1 and 2.

In the rear area of the vehicle are included a right and left pair ofrear wheels 3 b and a rear frame 11 acting as a vehicle frame extendingbetween the rear wheels 3 b. A driver's seat 50 is arranged slightlyforwardly of a center of an axle of the rear wheels, which is onlypartially depicted in two-dot chain line to provide good visibility forother devices.

A substantially horizontal mounting surface 12 is defined in the rearframe 11 in a peripheral area of the rear wheels 3 b, which is formed ofa floor material mounted on the rear frame 11 in this example. Theengine 20 is mounted in a vertical position, with an output shaftthereof being directed downward, on the mounting surface 12 in a centralportion of a transverse direction of the vehicle, rearwardly of thecenter of the axle of the rear wheels 3 b. A fuel tank 40 is arrangedforwardly of and adjacent to the engine 20.

The fuel tank 40 includes a main tank body 41 mounted under the driver'sseat 50, and an auxiliary tank body 42 mounted on one lateral side, onthe right side in the illustrated example, of the engine 20 in thetransverse direction of the vehicle. The main tank body 41 has arectangular shape with substantially the same width as the driver's seat50 and a length greater than that of the driver's seat 50 to provide alarge capacity in spite of its small depth to effectively use a spaceunder the driver's seat 50 limited vertically. The auxiliary tank body42 communicates with the main fuel tank 41, extending vertically on alateral side area of the engine 20 rearwardly of the driver's seat 50. Acylindrical oil-feeding unit 44 is provided in a top portion of theauxiliary tank body 42 with a fuel cap.

A canister 45 is mounted on the mounting surface 12 adjacent to theengine 20 on one lateral side (the right side in this example) of theengine 20 and rearwardly of and adjacent to the auxiliary fuel tank 43.A canister connecting port 42 b is provided in the top portion of theauxiliary tank body 42 to be connected to the canister 45 through a tubeor hose. Although not shown, the canister 45 is also connected to an airintake system of the engine 20 through a tube or hose. Since the engine20, auxiliary tank body 42 and canister 45 are adjacently arranged sothat they do not overlap as viewed from the top, the tubes or hoses forconnecting those devices may be shortened, which results in a compactpiping layout.

Apart from the above-noted engine 20, auxiliary tank body 42 andcanister 45, on the mounting surface 12 are mounted a muffler 21 on theother lateral side, the left side in this example, of the engine 20, anda battery unit 91 directly rearwardly of the canister 45. A bent, outerpipe frame 14 having a C-shape as viewed from the top is mounted tosurround those devices above the mounting surface 12. The outer pipeframe 14 is connected at opposite ends thereof to right and leftvertical frames 13 extending upwardly from the rear frame 11 rearwardlyof the driver's seat 50. Control cables are housed in an inner space ofthe outer pipe frame 14. The control cables include a cable foradjusting rotational speed of the engine 20, for example.

A partition 16 is preferably provided to separate between an engine areaand a driver's area in a longitudinal direction of the vehicle in orderto prevent heated air from blowing directly into the driver's seat 50.Since the fuel tank 40 divided into the main tank body 41 and auxiliarytank body 42 extends over a boundary between the engine area anddriver's area, it is preferable to allow the partition 16 to act as aretaining member to hold down the fuel tank 40 from above.

The specific embodiments of the present invention will be describedhereinafter in reference to the accompanying drawings. As shown in FIGS.3 and 5, the work vehicle according to the present invention isrepresented by a ride-on lawn mower including a vehicle body 1 supportedto a right and left pair of front wheels 3 a and a right and left pairof rear wheels 3 b. This type of ride-on lawn mower is also referred toas a zero-radius-turning mower, in which the right and left rear wheels2 b are independently controlled in forward/reverse drive speed. FIG. 3is a diagonal rear perspective view of the ride-on lawn mower, FIG. 4 isan overall side view thereof, and FIG. 5 is an overall top plan viewthereof.

The vehicle body 1 includes a front frame 10 and a rear frame 11 made ofsquare pipe material, for example, as main components. A mower unit 8 issuspended from the front frame 10 between the right and left pair offront wheels 3 a and the right and left pair of rear wheels 3 b to bevertically movable through an unillustrated link mechanism. The linkmechanism functions to vertically move the mower unit 8 in a horizontalposition through pedal control and lever control.

A boarding platform 51 made of sheet metal is provided to substantiallycover the entire front frame 10 from above. The boarding platform 51 hasa forwardly inclined surface formed by bending a front portion of theplatform, and a horizontal surface continued from the inclined surface.A rubber mat 51 a is laid over the horizontal surface, and a brake pedal52 urged to return to a non-braking position is arranged in a centralportion of the inclined surface. A driver's seat 50 is positioned onelevel higher rearwardly of the boarding platform 51. Fenders 53 andhandle units 6 having shift levers 60 are provided in lateral oppositesides of the driver's seat 50, respectively. Various control levers andcontrol buttons are arranged on a top surface of each fender 53. Agate-shaped ROPS frame 15 vertically extends rearwardly of the driver'sseat 50. The ROPS frame 15 is made of square pipe material and islongitudinally bendable about a transverse axis at intermediate portionsof right and left ROPS struts 15 a. More particularly, the ROPS frame 15is switchable between an upright standing position and a rearward lyingposition. In this type of ride-on lawn mower, a front area forwardly ofthe ROPS frame 15 of the vehicle body 1 is defined as a driver's section5, while a rear area rearwardly of the ROPS frame 15 of the vehicle body1 is defined as a drive section 2.

The rear frame 11 has an arched shape as viewed from the top with aright and left pair of straight frame portions 11 a extendinglongitudinally in the vicinity of the rear wheels 3 b and a curved frameportion 11 b projecting rearward for connecting the right and leftstraight frame portions 11 a to each other. A substantially horizontalmounting surface 12 for receiving various devices constituting the drivesection 2 is defined on the arched rear frame 11 rearwardly of thedriver's seat 50, which is formed as a top surface of a floor materialmounted on the rear frame 11 in the current embodiment. Vertical frames13 extend from an upper portion of the rear frame 11 to be spaced fromeach other by a predetermined interval. An outer pipe frame 14 having asimilar shape to the contour of the rear frame 11 is attached to upperportions of the vertical frames 13.

In the central part of the mounting surface 12 is mounted a gas engine20 with an output shaft thereof projecting downward. A fuel tank 40 ismounted over a region from a front area to a right-side area of theengine 20. As shown in FIGS. 6 to 8, the fuel tank 40 consists of a maintank body 41 mounted under the driver's seat 50 forwardly of the engine20, an auxiliary tank body 42 extending vertically on the right side ofthe engine 20 rearwardly of the driver's seat 50, and a neck-liketransitional portion 43 connecting the main tank body 41 to theauxiliary tank body 42. The main tank body 41 has a flat top surface andthus can be arranged efficiently along a lower surface of the driver'sseat 50. The auxiliary tank body 42 has a rectangular section elongatedtransversely of the vehicle body as viewed from the top and extendshigher than the main tank body 41 with a top portion 42 a thereofpositioned at a level beyond the outer pipe frame 14. An oil-feedingunit 44 is provided in a portion of the top portion 42 a transverselyoutward of the vehicle body, while a canister connecting port 42 b isprovided in a portion of the top portion 42 a transversely inward of thevehicle body (on the side adjacent to the engine). The oil-feeding unit44 consists of an oil-feeding pipe 44 b inserted into a hole formed in atop surface of the top portion 42 a, and a fuel cap 44 a attached to adistal end of the oil-feeding pipe 44 b. As understood from FIG. 7representing a sectional view taken on line H-H of FIG. 6, theoil-feeding pipe 44 b has a lower end positioned above a maximum heightof the main tank body 41. Since the canister connecting port 42 b isprovided substantially the highest position of the top surface of thetop portion 42 a, an upper space of the auxiliary tank body 42 includingthe oil-feeding pipe 44 b is an air layer. Pressure in the air layer ismaintained in a predetermined range by a two-way valve 48 disposed in afuel gas conduit (hose) 46 extending from the canister connecting port42 b. Thus, the air layer is maintained regardless of regular change ofthe position of the vehicle body, which prevents a fuel from enteringthe canister connecting port 42 b.

A canister 45 is placed on the mounting surface 12 adjacent to a rearside of the auxiliary tank body 42. The canister 45 is connected to anair intake system of the engine 20 through a purge conduit (hose) 47,and is connected to the canister connecting port 42 b through a fuel gasconduit (hose) 46. As the two-way valve 48 is disposed in the fuel gasconduit 46, an air layer is secured above the auxiliary tank body 42when a fuel is supplied, and pressure regulation is performed throughthe canister 45 when internal pressure of the tank is increased, ordecreased with use of the fuel.

In addition, a battery unit 91 is placed on the mounting surface 12adjacent to a rear side of the canister 45 (see FIG. 2). Further, amuffler 21 is placed on the mounting surface 12 on the opposite side ofthe battery unit 91 across the engine 20, that is, on the left side ofthe engine 20. A side portion of the muffler 21 faces an opening formedbetween the vertical frames 13, and thus can be effectively cooled. Anair cleaner 22 is mounted in a position higher than the engine 20 on theleft side of the engine 20. An engine cooling fan is provided above theengine 20 to be rotatable in unison with the output shaft 20 a of theengine 20, which is hidden in the drawings by an air-introducing housingfor covering the engine cooling fan from above.

In association with each of the right and left rear wheels 3 b, an HST(hydrostatic transmission) 30 and a gear transmission mechanism 31 fortransmitting drive power to the rear wheel 3 b are provided as shown inFIG. 9. A propelling-line belt transmission mechanism 32 includespulleys mounted between the output shaft 20 a of the engine and therespective HSTs 30 so that output from the engine is transmitted to eachHST. A shift control shaft for each HST (not shown) is linked to anassociated shift lever 60 through a control link mechanism so thatshifting operation is performed in response to longitudinal oscillatingmovement of each of the shift levers 60 mounted directly forwardly andlaterally of the driver's seat 50 (see FIG. 5).

With the above arrangement, either of the right and left shift levers 60is oscillated longitudinally to shift the HST 30 associated with theoscillated shift lever 60, which allows the right and left rear wheels 3b to be independently speed changed. More particularly, in this type ofride-on lawn mower, the right and left front wheels 3 a are followablysteered while the right and left rear wheels 3 b are independentlydriven for speed change, thereby to desirably produce a stop state forstopping the right and left rear wheels 3 b, a straight-forwardtraveling state for driving the right and left rear wheels 3 b forwardlyor reversely at the same speed, a gentle-turn state for driving theright and left wheels 3 b forwardly or reversely at different speeds, apivot-turn state for stopping one of the right and left rear wheels 3 bwhile driving the other of them forwardly or reversely, and a spin-turnstate for driving one of the right and left rear wheels 3 b forwardlywhile driving the other of them reversely.

The mower unit 8 is suspended from the front frame 10 between the rightand left pair of front wheels 3 a and the right and left pair of rearwheels 3 b to be vertically movable through the link mechanism 80. Themower unit 8 includes three blades 83 arranged in the transversedirection of the vehicle body within a mower deck 81. Each of the blades83 is fixed to a drive shaft 83 a supported to the mower deck 81. Amower-unit belt transmission mechanism 82 is provided to include pulleysmounted on the output shaft 20 a of the engine 20 and each drive shaft83 a, in which output from the engine 20 is transmitted to the mowerunit 8. As understood well from FIG. 9, the propelling-line belttransmission mechanism 32 and the mower-unit belt transmission mechanism82 use the output shaft 20 a of the engine 20 as an input shaft, andarranged at different levels independently of each other planarly. Thisarrangement allows constant-speed drive power to be transmitted to themower unit 8 regardless of a traveling speed or traveling state.

The fuel tank 40 is positioned under the driver's seat 50 without anymounting bracket to be fixed to the vehicle body. As shown in FIG. 8,the fuel tank 40 is mounted on a cross plate mounted on the rear frame11 through an elastic member such as rubber and laterally positionedthrough a projecting elastic member attached to the rear frame 11. Themain tank body 41 has a forward portion held down by a coupling platefor connecting the right and left fenders 53 to each other, and arearward portion, more particularly, a region around the transitionalarea 43, held down by a plate-like retaining member 16 from above. Theretaining member 16 is configured to section between an engine area anda driver's area in the longitudinal direction of the vehicle body toalso act as a partition in order to prevent heated air from the engine20 from blowing into directly to the driver's seat 50. Thus, theretaining member (partition) 16 has a transverse dimension and avertical dimension (height) over the entire width of the vehicle bodyand is fixed at opposite ends thereof to proximal end portions of theROPS struts 15 a. A tongue-like piece 16 a bent horizontally is providedin a central lower end of the retaining member 16 to fit into a recessformed in the transitional portion 43 between the main tank body 41 andthe auxiliary tank body 42, thereby to hold down the fuel tank 40.

Various levers and switches are provided in the top surfaces of thefenders 53 positioned laterally of the driver's seat 50. As apparentfrom FIGS. 3 to 5 showing an external appearance of the vehicle, thistype of ride-on mower does not include a hood for covering the enginearea. Naturally, such a hood may be provided.

Modified Embodiments

(1) In the first embodiment, the muffler 21 is placed on the side of theengine 20 along the longitudinal direction of the vehicle body. Instead,as shown in a modification of the ride-on lawn mower in FIG. 10, themuffler 21 may be placed rearwardly of the engine 20 along thetransverse direction of the vehicle body.

(2) In the first embodiment, the fuel tank 40 is held down from above bythe retaining member 16 acting also as the partition extendingtransversely of the vehicle body. Instead, the partition and retainingmember 16 may be separately provided. As shown in FIG. 10, for example,the main tank body 41 may be held down from above by a rod-likeretaining member 16A extending between cross members mounted forwardlyand rearwardly of the main tank body 41. In that case, the cross membermounted rearwardly of the main tank body 41 may act as a partition 16B.

(3) The fuel tank 40 shown as being mounted on the vehicle body in FIG.11 while shown solely in FIG. 12 has a slightly different constructionthan that in the first embodiment. While the fuel tank 40 consists ofthe main tank body 41, auxiliary tank body 42 and transitional portion43 in the same way as the first embodiment, the transitional portion 43extends upward to incline outwardly in the transverse direction of thevehicle body in order to position the auxiliary tank body 42 fartheroutwardly in the transverse direction of the vehicle body. In thismodified mode as well, the oil-feeding unit 44 and canister connectingport 42 b are provided in the top portion 42 a of the auxiliary tankbody 42 that is positioned at a level far higher than the main tank body41. The oil-feeding unit 44 according to the modified embodiment alsoconsists of the oil-feeding pipe 44 b inserted into the hole formed inthe top surface of the top portion 42 a, and the fuel cap 44 a attachedto the distal end of the oil-feeding pipe 44 b. As understood from FIG.13, the oil-feeding pipe 44 b has the lower end positioned above amaximum height of the transitional portion 43 extending upwardly furtherfrom the main tank body 41. In addition, since the canister connectingport 42 b is provided substantially the highest position of the topsurface of the top portion 42 a, an upper space of the auxiliary tankbody 42 including the oil-feeding pipe 44 b is an air layer. In thismodified embodiment as well, pressure in the air layer is maintained ina predetermined range by the two-way valve 48 disposed in the fuel gasconduit (hose) 46 extending from the canister connecting port 42 b.Thus, the air layer is maintained regardless of regular change of theposition of the vehicle body, which prevents the fuel from entering thecanister connecting port 42 b. As a result, the fuel enters the canister45 less easily even in the sloping ground.

(4) In the first embodiment, the present invention is applied to amid-mount lawn mower. Instead, the present invention is also applicableto a front-mount lawn mower or work vehicles other than the lawn mower.

INDUSTRIAL USABILITY

The present invention is applicable to a work vehicle with an engine anda fuel system mounted rearwardly.

What is claimed is:
 1. A fuel system for a work vehicle comprising: afuel tank comprising a main tank body and an auxiliary tank body; acanister; a fuel-gas introducing passage for connecting a top portion ofthe auxiliary tank body to the canister; the top portion of theauxiliary tank body being located higher than the main tank body whenthe fuel tank is installed on the work vehicle; and a fuel filling pipeextending through the top portion of the auxiliary tank body and havinga first end arranged outside the auxiliary tank body and a second endarranged within the auxiliary tank body.
 2. The fuel system of claim 1,wherein the first end is a fuel receiving port and the second end isarranged below the top portion of the auxiliary tank body.
 3. The fuelsystem of claim 1, wherein the fuel filling pipe is integrally formedwith the auxiliary tank body and the first end is axially shorter thanthe second end.
 4. The fuel system of claim 1, wherein the fuel gasintroducing passage is arranged in a fuel gas tube.
 5. The fuel systemof claim 1, further comprising a connecting port arranged on the topportion of the auxiliary tank body, said connecting port beingconnectable to the fuel-gas introducing passage.
 6. The fuel system ofclaim 5, wherein the second end of the fuel filling pipe is arrangedbelow the connecting port.
 7. The fuel system of claim 1, wherein thesecond end of the fuel filling pipe is arranged above an upper end ofthe main tank body.
 8. The fuel system of claim 1, wherein the send endof the fuel filling pipe extends below a half-way level of the auxiliarytank body.
 9. The fuel system of claim 1, wherein the fuel tank furthercomprises a transition section connecting the main tank body to theauxiliary tank body, said transition section allowing fuel introducedinto the auxiliary tank body to pass into the main tank body, and saidauxiliary tank body comprises an internal space arranged above each of:the second end of the fuel filling pipe; the main tank body; and thetransition section.
 10. The fuel system of claim 1, wherein the maintank body is mounted under a driver's seat.
 11. The fuel system of claim10, wherein the main tank body has substantially the same width as thedriver's seat, said width being measured in a direction between left andright sides of the work vehicle.
 12. The fuel system of claim 10,wherein the main tank body has a length greater than that of thedriver's seat, said length being measured in a direction between frontand back sides of the work vehicle.
 13. The fuel system of claim 10,wherein the main tank body has a flat top surface so as to be arrangedadjacent and below a lower surface of the driver's seat.
 14. The fuelsystem of claim 1, further comprising a valve disposed between oppositeends of the fuel-gas introducing passage.
 15. The fuel system of claim14, wherein the valve is two-way valve.
 16. A fuel system for a workvehicle comprising: a fuel tank comprising a main tank body and anauxiliary tank body; a canister; a fuel-gas introducing passage forconnecting a top portion of the auxiliary tank body to the canister; thetop portion of the auxiliary tank body being located higher than themain tank body when installed on the work vehicle; and a fuel fillingpipe extending through the top portion of the auxiliary tank body andcomprising: a fuel filling first end arranged outside the auxiliary tankbody; and a second end arranged above an uppermost end of the main tankbody.
 17. The fuel system of claim 16, wherein the fuel gas introducingpassage is arranged in a fuel gas tube and wherein the main tank bodyand the auxiliary tank body are integrally formed with one another. 18.A fuel system for a work vehicle comprising: a fuel tank comprising amain tank body and an auxiliary tank body; a canister; a fuel-gasintroducing passage for connecting a top portion of the auxiliary tankbody to the canister; the top portion of the auxiliary tank body beinglocated higher than a top portion of the main tank body when installedon the work vehicle; a connecting port arranged on the top portion ofthe auxiliary tank body and being connectable to one end of the fuel-gasintroducing passage; and a fuel filling pipe extending through the topportion of the auxiliary tank body and comprising a fuel filling endarranged outside the auxiliary tank body and an opposite end locatedwithin the auxiliary tank body and below the connecting port.
 19. Thefuel system of claim 18, wherein each of: the opposite end of the fuelfilling tube is spaced from a bottom end of the auxiliary tank body; thefuel gas introducing passage is arranged in a fuel gas tube; and themain tank body is larger in size than the auxiliary tank body.